1. Field of the Invention
The present invention relates to a mixed aqueous solution of L-lysine and L-threonine which includes L-lysine, L-threonine, and water, and which can be used as a feed ingredient or the like.
2. Brief Description of the Related Art
An L-lysine based aqueous solution has been reported to be used as a feed ingredient (see EP 111628 B). It has also been reported that when an acid ion, such as a sulfate ion, is added to an L-lysine based aqueous solution, an increase in the solubility of L-lysine, and the absence of precipitated crystals can be obtained (see EP 1035109 B). In addition, it has been reported that by electrodialyzing an L-lysine based aqueous solution to remove counter anions, a highly pure L-lysine base aqueous solution can be obtained (see FR 2822396 B).
Furthermore, it is preferred that products containing amino acids to be used as feed additives be in liquid form, since liquids are more convenient in handling when added to the feed, and uniform mixing can be more easily attained. In fact, amino acids are in liquid form are currently widely used in the feed industry. If the feed is distributed in a liquid form, it is generally preferred that the content of the amino acid be high, which means a lower content of water because of the following reasons: 1) lower transportation cost 2) lower risk of microbial development during the storage of a feed after mixing and 3) more suitable in formulating high nutrient density feed. For example, the L-lysine base aqueous solution is distributed at a concentration slightly below the saturation point to achieve the maximum concentration without risking precipitation of crystals.
Therefore, a liquid feed ingredient containing L-threonine is also desired, but has not been put into practical use yet.